Detached garage being built in Suburb of Detroit, MI

Contractor claims a dispute I am having with him is because "It is Code."
But somehow contractor's claim of "Code" is so un-reasonable for a detached
garage, it makes me think any similar actual rule would be for an attached
garage.

Cannot seem to find anything on internet for local building code (county or
city). So, How do I find out if contractor is bull***ting me or if there is
really a building code requirement.

No, I an not sure I do trust him on this issue.

TIA

Phil